1. Field of the Invention
Exemplary embodiments disclosed herein generally relate to electric arc engine welders, including those employing a welding gun for use in a welding operation and a wire feeder for supplying a consumable welding wire electrode to the welding gun. More particularly, exemplary embodiments disclosed herein relate to a grounding assembly for a welding wire feeder. The embodiments find particular application as (or in) portable electric arc engine welders, often used when the location of the welding operation is not expected to remain constant, such as, for example, welding operations at job sites which change day to day or welding operations covering large areas at a single job site. However, it is to be appreciated that the exemplary embodiments discussed herein are also amenable to other like applications.
2. Discussion of the Art
Electric arc engine welders are generally well known. Typically, in electric arc welders, a power source passes current between an electrode and a work piece. Often, the electrode is a continuous welding wire drawn from a supply of welding wire, such as a drum or reel, which is passed through a contact tip or gun on its way to being melted and deposited onto the work piece. Wire feeders are often used to advance the welding wire, preferably in a consistent and controllable manner, to the welding gun for use in the welding operation. Welding wire feeders can be manufactured in several forms, each optimized for a specific application. Common classifications of wire feeders include robotic wire feeders, portable wire feeders, tractor wire feeders and bench mount wire feeders.
Portable wire feeders are often used when the location of the welding operation or operations is likely to change or does not always remain constant (e.g., shipyards). This might include, for example, welding operations at job sites that change day-to-day or welding operations that cover a large area at a single job site. Examples of portable wire feeders are generally taught in the following U.S. patents: Bellefleur U.S. Pat. No. 4,665,300; Rybicki U.S. Pat. No. 6,213,375; Kroll U.S. Pat. No. 4,508,954; Chandler U.S. Pat. No. 6,225,596; Miller U.S. Pat. No. 5,410,126; Grimm U.S. Pat. No. 5,836,539; and Luo U.S. Pat. No. 6,705,563, all expressly incorporated herein by reference.
Preferably, portable wire feeders are able to supply their respective welding operations with welding wire in a manner much like that of a conventional stationary wire feeder. This is often more difficult in the portable wire feeder because it is likely to be subjected to repeated movement and used in connection with a wide range of work environments, many of which can be severe. In contrast, conventional stationary wire feeders are often used in controlled and unchanging environments, such as a work shop or factory floor. In addition to functioning like a stationary wire feeder, the portable wire feeder is preferably compact and lightweight enabling it to be more easily moved and used in confined work areas. Other desirable characteristics of portable wire feeders are ruggedness and durability.
In one conventional welding arrangement, a portable wire feeder is connected to a remotely positioned power source through one or more cables. The wire feeder is additionally connected to a welding gun by a guide hose. A motorized feeding system in the wire feeder employs rollers to advance or pay welding electrode wire. from a supply of wire (often a spool of wire) through the guide hose to the welding gun. For this purpose, the guide hose can include an internal tube for transporting the wire from the feeder to the gun, in addition to electrical wiring for providing power (such as control circuitry) to the gun. Optionally, the guide hose can further include passageways for transporting shielding gas to the gun and/or for circulating cooling fluid through or to the gun.
Through the one or more cables, the power source provides power to the motorized feeding system and control circuitry of the wire feeder, as well as welding current. With the power source grounded to a work piece to be welded, the provided welding current is selectively connected electrically to the electrode wire for creating a welding arc between the gun (whereat a portion of the welding wire is exposed) and the work piece. More particularly, a trigger on the gun can, when actuated, close a switch which causes a contactor in the wire feeder to provide welding current to the welding wire and thereby initiate the welding operation.
Power supplied to the wire feeder for the motorized feeding system and the feeder's control circuitry from the power source has to be grounded. For this purpose, the wire feeder is sometimes provided with a work sense lead, usually in the form of a wire extending from a side of the wire feeder (often oriented approximately normal relative to the work piece on which the wire feeder rests) with a clamp or clip at its end for removable attachment to the work piece. Alternatively, the work sense lead can include magnetic ground clamp for removably attaching to the work piece. Removably attaching the work sense lead to the work piece completes the power circuit. That is, power delivered to the wire feeder for the motorized feeding system and the feeder's control circuitry is grounded thereby creating a power circuit. In an alternate arrangement, one of the cables extending between the wire feeder and the power source can include suitable electrical wiring such that the wire feeder can be grounded back through the power source (i.e., the power circuit including the feeding system and control circuitry of the wire feeder is completed or looped through the power source). Unfortunately, this requires a cable separate from and in addition to the cable delivering welding current to the wire feeder.
One disadvantage of wire feeders having a work sense lead for grounding of the wire feeder directly to a work piece is that sometimes there is no convenient location for attaching the work sense lead to the work piece. This and/or a desire to have greater mobility of the wire feeder (i.e., movement of the wire feeder is limited by the length of the work sense lead) results in wire feeders being provided with relatively long work sense leads. The provision of a work sense lead, particularly a long work sense lead, can undesirably add to the number of cables and cable bundles accumulated about a work area. Wire feeders provided without work sense leads, as described in reference to the alternate arrangement discussed above, require an extra cable between the power source and the wire feeder. Like the provision of a work sense lead, requiring an extra cable also undesirably adds to the overall number of cables and cable bundles accumulated about a work area, in addition to undesirably requiring an operator to make extra cable connections.